1
|
Jaramillo AM, Vladar EK, Holguin F, Dickey BF, Evans CM. Emerging cell and molecular targets for treating mucus hypersecretion in asthma. Allergol Int 2024:S1323-8930(24)00046-7. [PMID: 38692992 DOI: 10.1016/j.alit.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 04/03/2024] [Indexed: 05/03/2024] Open
Abstract
Mucus provides a protective barrier that is crucial for host defense in the lungs. However, excessive or abnormal mucus can have pathophysiological consequences in many pulmonary diseases, including asthma. Patients with asthma are treated with agents that relax airway smooth muscle and reduce airway inflammation, but responses are often inadequate. In part, this is due to the inability of existing therapeutic agents to directly target mucus. Accordingly, there is a critical need to better understand how mucus hypersecretion and airway plugging are affected by the epithelial cells that synthesize, secrete, and transport mucus components. This review highlights recent advances in the biology of mucin glycoproteins with a specific focus on MUC5AC and MUC5B, the chief macromolecular components of airway mucus. An improved mechanistic understanding of key steps in mucin production and secretion will help reveal novel potential therapeutic strategies.
Collapse
Affiliation(s)
- Ana M Jaramillo
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Eszter K Vladar
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Fernando Holguin
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Burton F Dickey
- Department of Pulmonary Medicine, Anderson Cancer Center, University of Texas M.D., Houston, TX, USA
| | - Christopher M Evans
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, CO, USA.
| |
Collapse
|
2
|
Zhang L, Muirhead KJ, Syed ZA, Dimitriadis EK, Ten Hagen KG. A novel cysteine-rich adaptor protein is required for mucin packaging and secretory granule stability in vivo. Proc Natl Acad Sci U S A 2024; 121:e2314309121. [PMID: 38285943 PMCID: PMC10861859 DOI: 10.1073/pnas.2314309121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/02/2024] [Indexed: 01/31/2024] Open
Abstract
Mucins are large, highly glycosylated extracellular matrix proteins that line and protect epithelia of the respiratory, digestive, and urogenital tracts. Previous work has shown that mucins form large, interconnected polymeric networks that mediate their biological functions once secreted. However, how these large matrix molecules are compacted and packaged into much smaller secretory granules within cells prior to secretion is largely unknown. Here, we demonstrate that a small cysteine-rich adaptor protein is essential for proper packaging of a secretory mucin in vivo. This adaptor acts via cysteine bonding between itself and the cysteine-rich domain of the mucin. Loss of this adaptor protein disrupts mucin packaging in secretory granules, alters the mobile fraction within granules, and results in granules that are larger, more circular, and more fragile. Understanding the factors and mechanisms by which mucins and other highly glycosylated matrix proteins are properly packaged and secreted may provide insight into diseases characterized by aberrant mucin secretion.
Collapse
Affiliation(s)
- Liping Zhang
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892-4370
| | - Kayla J. Muirhead
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892-4370
- Ambry Genetics, Aliso Viejo, CA92656
| | - Zulfeqhar A. Syed
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892-4370
- Electron Microscopy Core Facility, National Heart, Lung and Blood Institute, NIH, Bethesda, MD20892
| | - Emilios K. Dimitriadis
- Trans-NIH Resource on Biomedical Engineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, NIH, Bethesda, MD20892
| | - Kelly G. Ten Hagen
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD20892-4370
| |
Collapse
|
3
|
Leo F, Lood R, Thomsson KA, Nilsson J, Svensäter G, Wickström C. Characterization of MdpS: an in-depth analysis of a MUC5B-degrading protease from Streptococcus oralis. Front Microbiol 2024; 15:1340109. [PMID: 38304711 PMCID: PMC10830703 DOI: 10.3389/fmicb.2024.1340109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 01/08/2024] [Indexed: 02/03/2024] Open
Abstract
Oral biofilms, comprising hundreds of bacteria and other microorganisms on oral mucosal and dental surfaces, play a central role in oral health and disease dynamics. Streptococcus oralis, a key constituent of these biofilms, contributes significantly to the formation of which, serving as an early colonizer and microcolony scaffold. The interaction between S. oralis and the orally predominant mucin, MUC5B, is pivotal in biofilm development, yet the mechanism underlying MUC5B degradation remains poorly understood. This study introduces MdpS (Mucin Degrading Protease from Streptococcus oralis), a protease that extensively hydrolyses MUC5B and offers an insight into its evolutionary conservation, physicochemical properties, and substrate- and amino acid specificity. MdpS exhibits high sequence conservation within the species and also explicitly among early biofilm colonizing streptococci. It is a calcium or magnesium dependent serine protease with strict physicochemical preferences, including narrow pH and temperature tolerance, and high sensitivity to increasing concentrations of sodium chloride and reducing agents. Furthermore, MdpS primarily hydrolyzes proteins with O-glycans, but also shows activity toward immunoglobulins IgA1/2 and IgM, suggesting potential immunomodulatory effects. Significantly, MdpS extensively degrades MUC5B in the N- and C-terminal domains, emphasizing its role in mucin degradation, with implications for carbon and nitrogen sequestration for S. oralis or oral biofilm cross-feeding. Moreover, depending on substrate glycosylation, the amino acids serine, threonine or cysteine triggers the enzymatic action. Understanding the interplay between S. oralis and MUC5B, facilitated by MdpS, has significant implications for the management of a healthy eubiotic oral microenvironment, offering potential targets for interventions aimed at modulating oral biofilm composition and succession. Additionally, since MdpS does not rely on O-glycan removal prior to extensive peptide backbone hydrolysis, the MdpS data challenges the current model of MUC5B degradation. These findings emphasize the necessity for further research in this field.
Collapse
Affiliation(s)
- Fredrik Leo
- Department of Oral Biology and Pathology, Faculty of Odontology, Malmö University, Malmö, Sweden
- Genovis AB, Kävlinge, Sweden
| | - Rolf Lood
- Genovis AB, Kävlinge, Sweden
- Department of Clinical Sciences Lund, Division of Infection Medicine, Faculty of Medicine, Lund University, Lund, Sweden
| | - Kristina A. Thomsson
- Proteomics Core Facility, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Jonas Nilsson
- Proteomics Core Facility, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Gunnel Svensäter
- Department of Oral Biology and Pathology, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Claes Wickström
- Department of Oral Biology and Pathology, Faculty of Odontology, Malmö University, Malmö, Sweden
| |
Collapse
|
4
|
Danilova NV, Chayka AV, Khomyakov VM, Oleynikova NA, Andreeva YY, Malkov PG, Sotnikova TN. [Mucins expression in gastric cancer: connection of MUC status with clinical, morphological and prognostic characteristics of the tumor]. Arkh Patol 2023; 85:16-28. [PMID: 36785958 DOI: 10.17116/patol20238501116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
OBJECTIVE Clarification of the prognostic value and relationship of MUC-phenotypes of gastric cancer with clinical and morphological parameters. MATERIAL AND METHODS Surgical material from 310 patients with a verified diagnosis of gastric cancer was studied. Samples were immunohistochemically stained with antibodies to MUC2, CD10, MUC5AC. The results were compared with clinical and morphological characteristics of gastric cancer and patient survival data. RESULTS The MUC-null and MUC-mix groups significantly differ in the prevalence of subtotal/total tumors from the MUC-I group (p=0.022 and p=0.007, respectively), where there are significantly fewer such tumors. Tubular tumors were more common in the MUC-null group compared to the MUC-G (p=0.026) and MUC-mix (p=0.006) groups, and there were fewer cases with the presence of "signet-ring" cells in the MUC-null group (p=0.000). When studying the discohesive histological type, the literature data on smaller tumor sizes and a lower frequency of lymph node metastasis for MUC-G status were not confirmed, but a more frequent proximal localization of MUC-I tumors was found (p=0.003). No statistically significant differences in survival were found in the analysis of the total sample. Differences in survival were found only in discohesive cancers, where the best survival was recorded for the MUC-null group, and the worst for the MUC-mix group (p=0.022). MUC status is not an independent predictor of gastric cancer (HR=1.662, p=0.093). CONCLUSION Between tumors with different MUC statuses, there were differences in localization and belonging to individual histological types. Significant differences in survival were found only for discohesive cancers with MUC-null and MUC-mix statuses. Separation of gastric cancers according to MUC status may have only limited predictive value in selected histological forms of cancer.
Collapse
Affiliation(s)
- N V Danilova
- Lomonosov Moscow State University, Moscow, Russia
| | - A V Chayka
- P. Hertsen Moscow Oncology Research Institute - branch of the National Medical Research Radiological Center, Moscow, Russia
| | - V M Khomyakov
- P. Hertsen Moscow Oncology Research Institute - branch of the National Medical Research Radiological Center, Moscow, Russia
| | | | - Yu Yu Andreeva
- Russian Medical Academy of Continuous Professional Education, Moscow, Russia
| | - P G Malkov
- Lomonosov Moscow State University, Moscow, Russia.,Russian Medical Academy of Continuous Professional Education, Moscow, Russia
| | - T N Sotnikova
- City clinical Hospital named after I.V. Davydovsky, Moscow, Russia
| |
Collapse
|
5
|
Hoang ON, Ermund A, Jaramillo AM, Fakih D, French CB, Flores JR, Karmouty-Quintana H, Magnusson JM, Fois G, Fauler M, Frick M, Braubach P, Hales JB, Kurten RC, Panettieri R, Vergara L, Ehre C, Adachi R, Tuvim MJ, Hansson GC, Dickey BF. Mucins MUC5AC and MUC5B Are Variably Packaged in the Same and in Separate Secretory Granules. Am J Respir Crit Care Med 2022; 206:1081-1095. [PMID: 35776514 PMCID: PMC9704839 DOI: 10.1164/rccm.202202-0309oc] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/01/2022] [Indexed: 01/27/2023] Open
Abstract
Rationale: MUC5AC (mucin 5AC, oligomeric gel-forming) and MUC5B (mucin 5B, oligomeric gel-forming) are the predominant secreted polymeric mucins in mammalian airways. They contribute differently to the pathogenesis of various muco-obstructive and interstitial lung diseases, and their genes are separately regulated, but whether they are packaged together or in separate secretory granules is not known. Objectives: To determine the packaging of MUC5AC and MUC5B within individual secretory granules in mouse and human airways under varying conditions of inflammation and along the proximal-distal axis. Methods: Lung tissue was obtained from mice stimulated to upregulate mucin production by the cytokines IL-1β and IL-13 or by porcine pancreatic elastase. Human lung tissue was obtained from donated normal lungs, biopsy samples of transplanted lungs, and explanted lungs from subjects with chronic obstructive pulmonary disease. MUC5AC and MUC5B were labeled with antibodies from different animal species or, in mice only, by transgenic chimeric mucin-fluorescent proteins and imaged using widefield deconvolution or Airyscan fluorescence microscopy. Measurements and Main Results: In both mouse and human airways, most secretory granules contained both mucins interdigitating within the granules. Smaller numbers of granules contained MUC5B alone, and even fewer contained MUC5AC alone. Conclusions: MUC5AC and MUC5B are variably stored both in the same and in separate secretory granules of both mice and humans. The high fraction of granules containing both mucins under a variety of conditions makes it unlikely that their secretion can be differentially controlled as a therapeutic strategy. This work also advances knowledge of the packaging of mucins within secretory granules to understand mechanisms of epithelial stress in the pathogenesis of chronic lung diseases.
Collapse
Affiliation(s)
- Oanh N. Hoang
- Department of Pulmonary Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Anna Ermund
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ana M. Jaramillo
- Department of Pulmonary Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Dalia Fakih
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Cory B. French
- Washington University School of Medicine, St. Louis, Missouri
| | - Jose R. Flores
- Washington University School of Medicine, St. Louis, Missouri
| | - Harry Karmouty-Quintana
- Division of Critical Care, Pulmonary, and Sleep Medicine, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Jesper M. Magnusson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Giorgio Fois
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Michael Fauler
- Institute of General Physiology, Ulm University, Ulm, Germany
| | - Manfred Frick
- Institute of General Physiology, Ulm University, Ulm, Germany
| | | | - Joshua B. Hales
- Washington University School of Medicine, St. Louis, Missouri
| | | | | | - Leoncio Vergara
- Institute of Biosciences and Technology, Texas A&M School of Medicine, Houston, Texas; and
| | - Camille Ehre
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Roberto Adachi
- Department of Pulmonary Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Michael J. Tuvim
- Department of Pulmonary Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Gunnar C. Hansson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Burton F. Dickey
- Department of Pulmonary Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas
| |
Collapse
|
6
|
Regulated Restructuring of Mucins During Secretory Granule Maturation In Vivo. Proc Natl Acad Sci U S A 2022; 119:e2209750119. [PMID: 36252017 PMCID: PMC9618048 DOI: 10.1073/pnas.2209750119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mucins are large, highly glycosylated transmembrane and secreted proteins that line and protect epithelial surfaces. However, the details of mucin biosynthesis and packaging in vivo are largely unknown. Here, we demonstrate that multiple distinct mucins undergo intragranular restructuring during secretory granule maturation in vivo, forming unique structures that are spatially segregated within the same granule. We further identify temporally-regulated genes that influence mucin restructuring, including those controlling pH (Vha16-1), Ca2+ ions (fwe) and Cl- ions (Clic and ClC-c). Finally, we show that altered mucin glycosylation influences the dimensions of these structures, thereby affecting secretory granule morphology. This study elucidates key steps and factors involved in intragranular, rather than intergranular segregation of mucins through regulated restructuring events during secretory granule maturation. Understanding how multiple distinct mucins are efficiently packaged into and secreted from secretory granules may provide insight into diseases resulting from defects in mucin secretion.
Collapse
|
7
|
Hu W, Feng P, Zhang M, Tian T, Wang S, Zhao B, Li Y, Wang S, Wu C. Endotoxins Induced ECM-Receptor Interaction Pathway Signal Effect on the Function of MUC2 in Caco2/HT29 Co-Culture Cells. Front Immunol 2022; 13:916933. [PMID: 35757703 PMCID: PMC9226665 DOI: 10.3389/fimmu.2022.916933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
Endotoxins are toxic substances that widely exist in the environment and can enter the intestine with food and other substances. Intestinal epithelial cells are protected by a mucus layer that contains MUC2 as its main structural component. However, a detailed understanding of the mechanisms involved in the function of the mucus barrier in endotoxin penetration is lacking. Here, we established the most suitable proportion of Caco-2/HT-29 co-culture cells as a powerful tool to evaluate the intestinal mucus layer. Our findings significantly advance current knowledge as focal adhesion and ECM-receptor interaction were identified as the two most significantly implicated pathways in MUC2 small interfering RNA (siRNA)-transfected Caco-2/HT-29 co-culture cells after 24 h of LPS stimulation. When the mucus layer was not intact, LPS was found to damage the tight junctions of Caco-2/HT29 co-cultured cells. Furthermore, LPS was demonstrated to inhibit the integrin-mediated focal adhesion structure and damage the matrix network structure of the extracellular and actin microfilament skeletons. Ultimately, LPS inhibited the interactive communication between the extracellular matrix and the cytoskeleton for 24 h in the siMUC2 group compared with the LPS(+) and LPS(-) groups. Overall, we recognized the potential of MUC2 as a tool for barrier function in several intestinal bacterial diseases.
Collapse
Affiliation(s)
- Wenxiang Hu
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Ping Feng
- College of Life Sciences, Yulin University, Yulin, China
| | - Mingming Zhang
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Tian Tian
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Shengxiang Wang
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Baoyu Zhao
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Yajie Li
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Shuo Wang
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| | - Chenchen Wu
- College of Animal Veterinary Medicine, Northwest A & F University, Yanling City, China
| |
Collapse
|
8
|
Ince D, Lucas TM, Malaker SA. Current strategies for characterization of mucin-domain glycoproteins. Curr Opin Chem Biol 2022; 69:102174. [PMID: 35752002 DOI: 10.1016/j.cbpa.2022.102174] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/02/2022] [Accepted: 05/19/2022] [Indexed: 11/18/2022]
Abstract
Glycosylation, and especially O-linked glycosylation, remains a critical blind spot in the understanding of post-translational modifications. Due to their nature as proteins defined by a large density and abundance of O-glycosylation, mucins present extra challenges in the analysis of their structure and function. However, recent breakthroughs in multiple areas of research have rendered mucin-domain glycoproteins more accessible to current characterization techniques. In particular, the adaptation of mucinases to glycoproteomic workflows, the manipulation of cellular glycosylation pathways, and the advances in synthetic methods to more closely mimic mucin domains have introduced new and exciting avenues to study mucin glycoproteins. Here, we summarize recent developments in understanding the structure and biological function of mucin domains and their associated glycans, from glycoproteomic tools and visualization methods to synthetic glycopeptide mimetics.
Collapse
Affiliation(s)
- Deniz Ince
- Department of Chemistry, Yale University, 275 Prospect St, New Haven, CT 06511, United States
| | - Taryn M Lucas
- Department of Chemistry, Yale University, 275 Prospect St, New Haven, CT 06511, United States
| | - Stacy A Malaker
- Department of Chemistry, Yale University, 275 Prospect St, New Haven, CT 06511, United States.
| |
Collapse
|
9
|
Sheng YH, Hasnain SZ. Mucus and Mucins: The Underappreciated Host Defence System. Front Cell Infect Microbiol 2022; 12:856962. [PMID: 35774401 PMCID: PMC9238349 DOI: 10.3389/fcimb.2022.856962] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 05/12/2022] [Indexed: 12/02/2022] Open
Abstract
The mucosal surfaces that form the boundary between the external environment and the underlying tissue are protected by a mucus barrier. Mucin glycoproteins, both secreted and cell surface mucins, are the major components of the barrier. They can exclude pathogens and toxins while hosting the commensal bacteria. In this review, we highlight the dynamic function of the mucins and mucus during infection, how this mucosal barrier is regulated, and how pathogens have evolved mechanisms to evade this defence system.
Collapse
Affiliation(s)
- Yong Hua Sheng
- Immunopathology Group, Mater Research Institute−The University of Queensland, Translational Research Institute, Brisbane, Qld, Australia
| | - Sumaira Z. Hasnain
- Immunopathology Group, Mater Research Institute−The University of Queensland, Translational Research Institute, Brisbane, Qld, Australia
- Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Qld, Australia
- *Correspondence: Sumaira Z. Hasnain,
| |
Collapse
|
10
|
Syed ZA, Zhang L, Ten Hagen KG. In vivo models of mucin biosynthesis and function. Adv Drug Deliv Rev 2022; 184:114182. [PMID: 35278522 PMCID: PMC9068269 DOI: 10.1016/j.addr.2022.114182] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 03/01/2022] [Accepted: 03/04/2022] [Indexed: 12/22/2022]
Abstract
The secreted mucus layer that lines and protects epithelial cells is conserved across diverse species. While the exact composition of this protective layer varies between organisms, certain elements are conserved, including proteins that are heavily decorated with N-acetylgalactosamine-based sugars linked to serines or threonines (O-linked glycosylation). These heavily O-glycosylated proteins, known as mucins, exist in many forms and are able to form hydrated gel-like structures that coat epithelial surfaces. In vivo studies in diverse organisms have highlighted the importance of both the mucin proteins as well as their constituent O-glycans in the protection and health of internal epithelia. Here, we summarize in vivo approaches that have shed light on the synthesis and function of these essential components of mucus.
Collapse
Affiliation(s)
- Zulfeqhar A Syed
- Developmental Glycobiology Section, NIDCR, National Institutes of Health, 30 Convent Drive, Bethesda, MD 20892-4370, United States
| | - Liping Zhang
- Developmental Glycobiology Section, NIDCR, National Institutes of Health, 30 Convent Drive, Bethesda, MD 20892-4370, United States
| | - Kelly G Ten Hagen
- Developmental Glycobiology Section, NIDCR, National Institutes of Health, 30 Convent Drive, Bethesda, MD 20892-4370, United States.
| |
Collapse
|
11
|
Kishimoto H, Ridley C, Thornton DJ. The lipophilic cyclic peptide cyclosporin A induces aggregation of gel-forming mucins. Sci Rep 2022; 12:6153. [PMID: 35418571 PMCID: PMC9008041 DOI: 10.1038/s41598-022-10125-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/04/2022] [Indexed: 12/05/2022] Open
Abstract
Cyclic peptides are good candidates for orally delivered therapeutics, however, issues remain in their development due to low intestinal permeability. Although some of the biological factors have been reported that regulate intestinal permeation of cyclic peptides, the influence of the mucus barrier, a major hurdle to epithelial drug delivery, on cyclic peptide bioavailability is unclear. In this study, we show that the lipophilic cyclic peptide, cyclosporin A (CsA), interacted with, and likely induced aggregation, of polymeric, gel-forming mucins (MUC2, MUC5AC and MUC5B) which underpin the mucus gel-networks in the gastrointestinal tract. Under similar conditions, two other cyclic peptides (daptomycin and polymyxin B) did not cause mucin aggregation. Using rate-zonal centrifugation, purified MUC2, MUC5AC and MUC5B mucins sedimented faster in the presence of CsA, with a significant increase in mucins in the pellet fraction. In contrast, mucin sedimentation profiles were largely unaltered after treatment with daptomycin or polymyxin B. CsA increased MUC5B sedimentation was concentration-dependent, and sedimentation studies using recombinant mucin protein domains suggests CsA most likely causes aggregation of the relatively non-O-glycosylated N-terminal and C-terminal regions of MUC5B. Furthermore, the aggregation of the N-terminal region, but not the C-terminal region, was affected by pH. CsA has partially N-methylated amide groups, this unique molecular structure, not present in daptomycin and polymyxin B, may potentially be involved in interaction with gel-forming mucin. Taken together, our results indicate that the interaction of gel-forming mucins with the cyclic peptide CsA is mediated at the N- and C-terminal domains of mucin polymers under physiological conditions. Our findings demonstrate that the mucus barrier is an important physiological factor regulating the intestinal permeation of cyclic peptides in vivo.
Collapse
Affiliation(s)
- Hisanao Kishimoto
- Department of Biopharmaceutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1, Horinouchi, Hachioji, Tokyo, 192-0392, Japan. .,Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK.
| | - Caroline Ridley
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK
| | - David J Thornton
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre, The University of Manchester, Oxford Road, Manchester, M13 9PT, UK.
| |
Collapse
|
12
|
Argüeso P. Human ocular mucins: The endowed guardians of sight. Adv Drug Deliv Rev 2022; 180:114074. [PMID: 34875287 PMCID: PMC8724396 DOI: 10.1016/j.addr.2021.114074] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/22/2021] [Accepted: 11/30/2021] [Indexed: 01/03/2023]
Abstract
Mucins are an ancient group of glycoproteins that provide viscoelastic, lubricating and hydration properties to fluids bathing wet surfaced epithelia. They are involved in the protection of underlying tissues by forming a barrier with selective permeability properties. The expression, processing and spatial distribution of mucins are often determined by organ-specific requirements that in the eye involve protecting against environmental insult while allowing the passage of light. The human ocular surface epithelia have evolved to produce an extremely thin and watery tear film containing a distinct soluble mucin product secreted by goblet cells outside the visual axis. The adaptation to the ocular environment is notably evidenced by the significant contribution of transmembrane mucins to the tear film, where they can occupy up to one-quarter of its total thickness. This article reviews the tissue-specific properties of human ocular mucins, methods of isolation and detection, and current approaches to model mucin systems recapitulating the human ocular surface mucosa. This knowledge forms the fundamental basis to develop applications with a promising biological and clinical impact.
Collapse
Affiliation(s)
- Pablo Argüeso
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, United States.
| |
Collapse
|
13
|
Arnhold J. Heme Peroxidases at Unperturbed and Inflamed Mucous Surfaces. Antioxidants (Basel) 2021; 10:antiox10111805. [PMID: 34829676 PMCID: PMC8614983 DOI: 10.3390/antiox10111805] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 01/15/2023] Open
Abstract
In our organism, mucous surfaces are important boundaries against the environmental milieu with defined fluxes of metabolites through these surfaces and specific rules for defense reactions. Major mucous surfaces are formed by epithelia of the respiratory system and the digestive tract. The heme peroxidases lactoperoxidase (LPO), myeloperoxidase (MPO), and eosinophil peroxidase (EPO) contribute to immune protection at epithelial surfaces and in secretions. Whereas LPO is secreted from epithelial cells and maintains microbes in surface linings on low level, MPO and EPO are released from recruited neutrophils and eosinophils, respectively, at inflamed mucous surfaces. Activated heme peroxidases are able to oxidize (pseudo)halides to hypohalous acids and hypothiocyanite. These products are involved in the defense against pathogens, but can also contribute to cell and tissue damage under pathological conditions. This review highlights the beneficial and harmful functions of LPO, MPO, and EPO at unperturbed and inflamed mucous surfaces. Among the disorders, special attention is directed to cystic fibrosis and allergic reactions.
Collapse
Affiliation(s)
- Jürgen Arnhold
- Medical Faculty, Institute of Medical Physics and Biophysics, Leipzig University, 04107 Leipzig, Germany
| |
Collapse
|
14
|
Marczynski M, Kimna C, Lieleg O. Purified mucins in drug delivery research. Adv Drug Deliv Rev 2021; 178:113845. [PMID: 34166760 DOI: 10.1016/j.addr.2021.113845] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/02/2021] [Accepted: 06/16/2021] [Indexed: 12/20/2022]
Abstract
One of the main challenges in the field of drug delivery remains the development of strategies to efficiently transport pharmaceuticals across mucus barriers, which regulate the passage and retention of molecules and particles in all luminal spaces of the body. A thorough understanding of the molecular mechanisms, which govern such selective permeability, is key for achieving efficient translocation of drugs and drug carriers. For this purpose, model systems based on purified mucins can contribute valuable information. In this review, we summarize advances that were made in the field of drug delivery research with such mucin-based model systems: First, we give an overview of mucin purification procedures and discuss the suitability of model systems reconstituted from purified mucins to mimic native mucus. Then, we summarize techniques to study mucin binding. Finally, we highlight approaches that made use of mucins as building blocks for drug delivery platforms or employ mucins as active compounds.
Collapse
|
15
|
Carpenter J, Wang Y, Gupta R, Li Y, Haridass P, Subramani DB, Reidel B, Morton L, Ridley C, O'Neal WK, Buisine MP, Ehre C, Thornton DJ, Kesimer M. Assembly and organization of the N-terminal region of mucin MUC5AC: Indications for structural and functional distinction from MUC5B. Proc Natl Acad Sci U S A 2021; 118:e2104490118. [PMID: 34548396 PMCID: PMC8488587 DOI: 10.1073/pnas.2104490118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2021] [Indexed: 12/16/2022] Open
Abstract
Elevated levels of MUC5AC, one of the major gel-forming mucins in the lungs, are closely associated with chronic obstructive lung diseases such as chronic bronchitis and asthma. It is not known, however, how the structure and/or gel-making properties of MUC5AC contribute to innate lung defense in health and drive the formation of stagnant mucus in disease. To understand this, here we studied the biophysical properties and macromolecular assembly of MUC5AC compared to MUC5B. To study each native mucin, we used Calu3 monomucin cultures that produced MUC5AC or MUC5B. To understand the macromolecular assembly of MUC5AC through N-terminal oligomerization, we expressed a recombinant whole N-terminal domain (5ACNT). Scanning electron microscopy and atomic force microscopy imaging indicated that the two mucins formed distinct networks on epithelial and experimental surfaces; MUC5B formed linear, infrequently branched multimers, whereas MUC5AC formed tightly organized networks with a high degree of branching. Quartz crystal microbalance-dissipation monitoring experiments indicated that MUC5AC bound significantly more to hydrophobic surfaces and was stiffer and more viscoelastic as compared to MUC5B. Light scattering analysis determined that 5ACNT primarily forms disulfide-linked covalent dimers and higher-order oligomers (i.e., trimers and tetramers). Selective proteolytic digestion of the central glycosylated region of the full-length molecule confirmed that MUC5AC forms dimers and higher-order oligomers through its N terminus. Collectively, the distinct N-terminal organization of MUC5AC may explain the more adhesive and unique viscoelastic properties of branched, highly networked MUC5AC gels. These properties may generate insight into why/how MUC5AC forms a static, "tethered" mucus layer in chronic muco-obstructive lung diseases.
Collapse
Affiliation(s)
- Jerome Carpenter
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Yang Wang
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Richa Gupta
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Yuanli Li
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Prashamsha Haridass
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Durai B Subramani
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Boris Reidel
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Lisa Morton
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Caroline Ridley
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom
- The Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Wanda K O'Neal
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - Marie-Pierre Buisine
- UMR9020-U1277 CANTHER (Cancer Heterogeneity Plasticity and Resistance to Therapies), Université Lille, CNRS, Inserm, CHU Lille, F5900 Lille, France
| | - Camille Ehre
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| | - David J Thornton
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom
- The Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Mehmet Kesimer
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248;
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27517-7248
| |
Collapse
|
16
|
Fang J, Wang H, Zhou Y, Zhang H, Zhou H, Zhang X. Slimy partners: the mucus barrier and gut microbiome in ulcerative colitis. Exp Mol Med 2021; 53:772-787. [PMID: 34002011 PMCID: PMC8178360 DOI: 10.1038/s12276-021-00617-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/14/2021] [Accepted: 01/31/2021] [Indexed: 02/08/2023] Open
Abstract
Ulcerative colitis (UC) is a chronic recurrent intestinal inflammatory disease characterized by high incidence and young onset age. Recently, there have been some interesting findings in the pathogenesis of UC. The mucus barrier, which is composed of a mucin complex rich in O-glycosylation, not only provides nutrients and habitat for intestinal microbes but also orchestrates the taming of germs. In turn, the gut microbiota modulates the production and secretion of mucins and stratification of the mucus layers. Active bidirectional communication between the microbiota and its 'slimy' partner, the mucus barrier, seems to be a continually performed concerto, maintaining homeostasis of the gut ecological microenvironment. Any abnormalities may induce a disorder in the gut community, thereby causing inflammatory damage. Our review mainly focuses on the complicated communication between the mucus barrier and gut microbiome to explore a promising new avenue for UC therapy.
Collapse
Affiliation(s)
- Jian Fang
- grid.203507.30000 0000 8950 5267Department of Preventive Medicine, Zhejiang Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang People’s Republic of China ,grid.412551.60000 0000 9055 7865College of Medicine, Shaoxing University, 508 Huancheng Road, Shaoxing, Zhejiang Province People’s Republic of China
| | - Hui Wang
- grid.415644.60000 0004 1798 6662Department of Colorectal Surgery, Shaoxing people’s Hospital, 568 North Zhongxing Road, Shaoxing, Zhejiang Province People’s Republic of China
| | - Yuping Zhou
- grid.203507.30000 0000 8950 5267The Affiliated Hospital of Medical School, Ningbo University, 247 Renmin Road, Ningbo, Zhejiang People’s Republic of China
| | - Hui Zhang
- grid.203507.30000 0000 8950 5267Department of Preventive Medicine, Zhejiang Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang People’s Republic of China
| | - Huiting Zhou
- grid.203507.30000 0000 8950 5267Department of Preventive Medicine, Zhejiang Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang People’s Republic of China
| | - Xiaohong Zhang
- grid.203507.30000 0000 8950 5267Department of Preventive Medicine, Zhejiang Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, 818 Fenghua Road, Ningbo, Zhejiang People’s Republic of China
| |
Collapse
|
17
|
Javitt G, Khmelnitsky L, Albert L, Bigman LS, Elad N, Morgenstern D, Ilani T, Levy Y, Diskin R, Fass D. Assembly Mechanism of Mucin and von Willebrand Factor Polymers. Cell 2020; 183:717-729.e16. [PMID: 33031746 PMCID: PMC7599080 DOI: 10.1016/j.cell.2020.09.021] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 06/25/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022]
Abstract
The respiratory and intestinal tracts are exposed to physical and biological hazards accompanying the intake of air and food. Likewise, the vasculature is threatened by inflammation and trauma. Mucin glycoproteins and the related von Willebrand factor guard the vulnerable cell layers in these diverse systems. Colon mucins additionally house and feed the gut microbiome. Here, we present an integrated structural analysis of the intestinal mucin MUC2. Our findings reveal the shared mechanism by which complex macromolecules responsible for blood clotting, mucociliary clearance, and the intestinal mucosal barrier form protective polymers and hydrogels. Specifically, cryo-electron microscopy and crystal structures show how disulfide-rich bridges and pH-tunable interfaces control successive assembly steps in the endoplasmic reticulum and Golgi apparatus. Remarkably, a densely O-glycosylated mucin domain performs an organizational role in MUC2. The mucin assembly mechanism and its adaptation for hemostasis provide the foundation for rational manipulation of barrier function and coagulation.
Collapse
Affiliation(s)
- Gabriel Javitt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lev Khmelnitsky
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lis Albert
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Lavi Shlomo Bigman
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nadav Elad
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - David Morgenstern
- De Botton Institute for Protein Profiling, Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tal Ilani
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yaakov Levy
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ron Diskin
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
| |
Collapse
|
18
|
Dey P, Rajdev P, Pramanik P, Haag R, Ghosh S. Synthesis of a Cylindrical Micelle from Hydrophilic Polymers Connected with a Single Supramolecular Structure-Directing Unit. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01493] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | - Rainer Haag
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | | |
Collapse
|
19
|
Xie Y, Lu L, Tang XX, Moninger TO, Huang TJ, Stoltz DA, Welsh MJ. Acidic Submucosal Gland pH and Elevated Protein Concentration Produce Abnormal Cystic Fibrosis Mucus. Dev Cell 2020; 54:488-500.e5. [PMID: 32730755 DOI: 10.1016/j.devcel.2020.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/03/2020] [Accepted: 07/07/2020] [Indexed: 10/24/2022]
Abstract
In response to respiratory insults, airway submucosal glands secrete copious mucus strands to increase mucociliary clearance and protect the lung. However, in cystic fibrosis, stimulating submucosal glands has the opposite effect, disrupting mucociliary transport. In cystic fibrosis (CF) pigs, loss of cystic fibrosis transmembrane conductance regulator (CFTR) anion channels produced submucosal gland mucus that was abnormally acidic with an increased protein concentration. To test whether these variables alter mucus, we produced a microfluidic model of submucosal glands using mucus vesicles from banana slugs. Acidic pH and increased protein concentration decreased mucus gel volume and increased mucus strand elasticity and tensile strength. However, once mucus strands were formed, changing pH or protein concentration largely failed to alter the biophysical properties. Likewise, raising pH or apical perfusion did not improve clearance of mucus strands from CF airways. These findings reveal mechanisms responsible for impaired mucociliary transport in CF and have important implications for potential treatments.
Collapse
Affiliation(s)
- Yuliang Xie
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Lin Lu
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Xiao Xiao Tang
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Thomas O Moninger
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Tony Jun Huang
- Department of Mechanical Engineering and Materials Science, Pratt School of Engineering, Duke University, Durham, NC 27708, USA
| | - David A Stoltz
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Molecular Physiology and Biophysics, Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Michael J Welsh
- Department of Internal Medicine and Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Molecular Physiology and Biophysics, Roy J and Lucille A Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| |
Collapse
|
20
|
Abstract
Generating the barriers that protect our inner surfaces from bacteria and other challenges requires large glycoproteins called mucins. These come in two types, gel-forming and transmembrane, all characterized by large, highly O-glycosylated mucin domains that are diversely decorated by Golgi glycosyltransferases to become extended rodlike structures. The general functions of mucins on internal epithelial surfaces are to wash away microorganisms and, even more importantly, to build protective barriers. The latter function is most evident in the large intestine, where the inner mucus layer separates the numerous commensal bacteria from the epithelial cells. The host's conversion of MUC2 to the outer mucus layer allows bacteria to degrade the mucin glycans and recover the energy content that is then shared with the host. The molecular nature of the mucins is complex, and how they construct the extracellular complex glycocalyx and mucus is poorly understood and a future biochemical challenge.
Collapse
Affiliation(s)
- Gunnar C Hansson
- Department of Medical Biochemistry, University of Gothenburg, SE 405 30 Gothenburg, Sweden;
| |
Collapse
|
21
|
Fakih D, Rodriguez-Piñeiro AM, Trillo-Muyo S, Evans CM, Ermund A, Hansson GC. Normal murine respiratory tract has its mucus concentrated in clouds based on the Muc5b mucin. Am J Physiol Lung Cell Mol Physiol 2020; 318:L1270-L1279. [PMID: 32348677 DOI: 10.1152/ajplung.00485.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The organization of the normal airway mucus system differs in small experimental animals from that in humans and large mammals. To address normal murine airway mucociliary clearance, Alcian blue-stained mucus transport was measured ex vivo on tracheal tissues of naïve C57BL/6, Muc5b-/-, Muc5ac-/-, and EGFP-tagged Muc5b reporter mice. Close to the larynx with a few submucosal glands, the mucus appeared as thick bundles. More distally in the trachea and in large bronchi, Alcian blue-stained mucus was organized in cloud-like formations based on the Muc5b mucin. On tilted tissue, the mucus clouds moved upward toward the larynx with an average velocity of 12 µm/s compared with 20 µm/s for beads not associated with clouds. In Muc5ac-/- mice, Muc5b formed mucus strands attached to the tissue surface, while in Muc5b-/- mice, Muc5ac had a more variable appearance. The normal mouse lung mucus thus appears as discontinuous clouds, clearly different from the stagnant mucus layer in diseased lungs.
Collapse
Affiliation(s)
- Dalia Fakih
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | | | - Sergio Trillo-Muyo
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | | | - Anna Ermund
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Gunnar C Hansson
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
22
|
Abstract
Membrane mucins cover most mucosal surfaces throughout the human body. The intestine harbors complex population of microorganisms (the microbiota) and numerous exogenous molecules that can harm the epithelium. In the colon, where the microbial burden is high, a mucus barrier forms the first line of defense by keeping bacteria away from the epithelial cells. In the small intestine where the mucus layer is less organized, microbes are kept at bay by peristalsis and antimicrobial peptides. Additionally, a dense glycocalyx consisting of extended and heavily glycosylated membrane mucins covers the surface of enterocytes. Whereas many aspects of mucosal barriers are being discovered, the function of membrane mucins remains a largely overlooked topic, mainly because we lack the necessary reagents and experimental animal models to investigate these large glycoproteins. In this Cell Science at a Glance article and accompanying poster, we highlight central concepts of membrane mucin biology and the role of membrane mucins as integral components of intestinal mucosal barriers. We also present the current consensus concerning the role of membrane mucins in host-microbe interactions. Moreover, we discuss how regulatory circuits that govern membrane mucins in the healthy gut display strong overlap with pathways that are perturbed during chronic inflammation. Finally, we review how dysregulation of intestinal membrane mucins may contribute to human diseases, such as inflammation and cancer.
Collapse
Affiliation(s)
- Thaher Pelaseyed
- Dept. Medical Biochemistry, University of Gothenburg, Box 440, 40530 Gothenburg, Sweden
| | - Gunnar C Hansson
- Dept. Medical Biochemistry, University of Gothenburg, Box 440, 40530 Gothenburg, Sweden
| |
Collapse
|
23
|
Liao YSJ, Kuan SP, Guevara MV, Collins EN, Atanasova KR, Dadural JS, Vogt K, Schurmann V, Bravo L, Eken E, Sponchiado M, Reznikov LR. Acid exposure disrupts mucus secretion and impairs mucociliary transport in neonatal piglet airways. Am J Physiol Lung Cell Mol Physiol 2020; 318:L873-L887. [PMID: 32160007 DOI: 10.1152/ajplung.00025.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Tenacious mucus produced by tracheal and bronchial submucosal glands is a defining feature of several airway diseases, including cystic fibrosis (CF). Airway acidification as a driving force of CF airway pathology has been controversial. Here we tested the hypothesis that transient airway acidification produces pathologic mucus and impairs mucociliary transport. We studied pigs challenged with intra-airway acid. Acid had a minimal effect on mucus properties under basal conditions. However, cholinergic stimulation in acid-challenged pigs revealed retention of mucin 5B (MUC5B) in the submucosal glands, decreased concentrations of MUC5B in the lung lavage fluid, and airway obstruction. To more closely mimic a CF-like environment, we also examined mucus secretion and transport following cholinergic stimulation under diminished bicarbonate and chloride transport conditions ex vivo. Under these conditions, airways from acid-challenged pigs displayed extensive mucus films and decreased mucociliary transport. Pretreatment with diminazene aceturate, a small molecule with ability to inhibit acid detection through blockade of the acid-sensing ion channel (ASIC) at the doses provided, did not prevent acid-induced pathologic mucus or transport defects but did mitigate airway obstruction. These findings suggest that transient airway acidification early in life has significant impacts on mucus secretion and transport properties. Furthermore, they highlight diminazene aceturate as an agent that might be beneficial in alleviating airway obstruction.
Collapse
Affiliation(s)
- Yan Shin J Liao
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Shin Ping Kuan
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Maria V Guevara
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Emily N Collins
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Kalina R Atanasova
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Joshua S Dadural
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Kevin Vogt
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Veronica Schurmann
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Laura Bravo
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Eda Eken
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Mariana Sponchiado
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| | - Leah R Reznikov
- Department of Physiological Sciences University of Florida, Gainesville, Florida
| |
Collapse
|
24
|
Hughes GW, Ridley C, Collins R, Roseman A, Ford R, Thornton DJ. The MUC5B mucin polymer is dominated by repeating structural motifs and its topology is regulated by calcium and pH. Sci Rep 2019; 9:17350. [PMID: 31758042 PMCID: PMC6874590 DOI: 10.1038/s41598-019-53768-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 11/01/2019] [Indexed: 01/15/2023] Open
Abstract
The polymeric mucin MUC5B provides the structural and functional framework of respiratory mucus, conferring both viscoelastic and antimicrobial properties onto this vital protective barrier. Whilst it is established that MUC5B forms disulfide-linked linear polymers, how this relates to their packaging in secretory granules, and their molecular form in mucus remain to be fully elucidated. Moreover, the role of the central heavily O-glycosylated mucin domains in MUC5B conformation is incompletely described. Here we have completed a detailed structural analysis on native MUC5B polymers purified from saliva and subsequently investigated how MUC5B conformation is affected by changes in calcium concentration and pH, factors important for mucin intragranular packaging and post-secretory expansion. The results identify that MUC5B has a beaded structure repeating along the polymer axis and suggest that these repeating motifs arise from distinct glycosylation patterns. Moreover, we demonstrate that the conformation of these highly entangled linear polymers is sensitive to calcium concentration and changes in pH. In the presence of calcium (Ca2+, 10 mM) at pH 5.0, MUC5B adopted a compact conformation which was lost either upon removal of calcium with EGTA, or by increasing the pH to 7.4. These results suggest a pathway of mucin collapse to enable intracellular packaging and mechanisms driving mucin expansion following secretion. They also point to the importance of the tight control of calcium and pH during different stages of mucin biosynthesis and secretion, and in the generation of correct mucus barrier properties.
Collapse
Affiliation(s)
- Gareth W Hughes
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK.,School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK
| | - Caroline Ridley
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK.,School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK
| | - Richard Collins
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK
| | - Alan Roseman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK
| | - Robert Ford
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK
| | - David J Thornton
- Wellcome Trust Centre for Cell-Matrix Research, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK. .,Lydia Becker Institute for Immunology and Inflammation, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK. .,School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, M13 9PT, UK.
| |
Collapse
|
25
|
Abstract
Mucociliary clearance is a crucial component of innate defense of the lung. In respiratory diseases, such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis, mucus with abnormal properties contributes to obstruction of the airways. The failure in function of mucus in airway clearance and pathogen protection leads to chronic infection and risk of death. Polymeric mucins (MUC5AC and MUC5B) provide the structural framework of the airway mucus gel. The intracellular synthesis and assembly of these enormous, polymeric O-linked glycoproteins is a complex, multistage process involving intra- and intermolecular disulfide bond formation and extensive addition of O-glycan chains. The fully formed polymers are packaged in a highly organized and condensed form within secretory granules inside specialized secretory cells, and after the appropriate stimulus, mucins are released and expand to form mucus. This short article brings together the current knowledge on the different steps in the production of mucin polymers and the molecular mechanisms that condense them into a packaged form in secretory granules. It is by unraveling the molecular mechanisms that control intracellular mucin supramolecular structure that we might gain new insight into what determines mucus gel properties in health and disease.
Collapse
|
26
|
Abstract
Dysregulation of gel-forming mucins is associated with many airway diseases. Better knowledge of the pathophysiological mechanisms linking mucins and respiratory diseases will advance the understanding of their pathogenesis and should provide opportunities to develop new therapeutic compounds for treatment. MUC5B and MUC5AC are the two main gel-forming mucins in the respiratory tract. The organization in domains and the expression profile of mouse Muc5b are very similar to those in humans, which makes the mouse a relevant model for studies of the translational activities of human mucins. To assess the in vivo biological functions of Muc5b, a mouse reporter tagged in frame with the green fluorescent protein marker has been engineered by homologous recombination. The proof of concept that this reporter model may be informative for translational studies was confirmed by the finding that interleukin-13 administration in living mice upregulated Muc5b production.
Collapse
|
27
|
Abstract
The respiratory system is protected from inhaled particles and microbes by the mucociliary system. This system differs between animal species, where pigs and humans have numerous submucosal glands. The polymer-forming mucin, MUC5B, is packed in a highly organized way in granules of the mucus-secreting cells in the glands. Upon secretion, the packed MUC5B is flushed out by a chloride- and bicarbonate-rich fluid from the cystic fibrosis transmembrane conductance regulator-expressing serosal cells located at the most distal part of the gland. The bicarbonate raises the pH and removes calcium from the N terminus of MUC5B, allowing the mucin to be pulled out into a linear polymer. Thousands of such polymers gather in bundles in the submucosal gland duct, and these bundles appear at the opening of the glands. They are moved by the beating cilia, and sweep over the airway surface and are patchily coated with the MUC5AC mucin from the surface goblet cells. The movement of these bundles is controlled by the MUC5AC mucin attachment/detachment to the goblet cells. Thus, higher animals with submucosal glands and large diameters of the proximal airways are efficiently cleaned by the thick mucus bundles sweeping the airway surface and moving particles and bacteria toward the larynx.
Collapse
|
28
|
Demouveaux B, Gouyer V, Robbe-Masselot C, Gottrand F, Narita T, Desseyn JL. Mucin CYS domain stiffens the mucus gel hindering bacteria and spermatozoa. Sci Rep 2019; 9:16993. [PMID: 31740753 PMCID: PMC6861317 DOI: 10.1038/s41598-019-53547-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 10/31/2019] [Indexed: 12/14/2022] Open
Abstract
Mucus is the first biological barrier encountered by particles and pathogenic bacteria at the surface of secretory epithelia. The viscoelasticity of mucus is governed in part by low energy interactions that are difficult to assess. The CYS domain is a good candidate to support low energy interactions between GFMs and/or mucus constituents. Our aim was to stiffen the mucus from HT29-MTX cell cocultures and the colon of mice through the delivery of a recombinant protein made of hydrophobic CYS domains and found in multiple copies in polymeric mucins. The ability of the delivery of a poly-CYS molecule to stiffen mucus gels was assessed by probing cellular motility and particle diffusion. We demonstrated that poly-CYS enrichment decreases mucus permeability and hinders displacement of pathogenic flagellated bacteria and spermatozoa. Particle tracking microrheology showed a decrease of mucus diffusivity. The empirical obstruction scaling model evidenced a decrease of mesh size for mouse mucus enriched with poly-CYS molecules. Our data bring evidence that enrichment with a protein made of CYS domains stiffens the mucin network to provide a more impermeable and protective mucus barrier than mucus without such enrichment.
Collapse
Affiliation(s)
| | - Valérie Gouyer
- Inserm, Univ. Lille, CHU Lille, LIRIC UMR 995, F-59000, Lille, France
| | - Catherine Robbe-Masselot
- CNRS, Univ. Lille, UMR 8576, Unité de Glycobiologie Structurale et Fonctionnelle (UGSF), F-59000, Lille, France
| | - Frédéric Gottrand
- Inserm, Univ. Lille, CHU Lille, LIRIC UMR 995, F-59000, Lille, France
| | - Tetsuharu Narita
- CNRS, PSL Research University, UPMC Univ. Paris 06, ESPCI Paris, UMR 7615, Laboratoire Sciences et Ingénierie de la Matière Molle, 10 rue Vauquelin, 75231, Paris, Cedex 05, France.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Jean-Luc Desseyn
- Inserm, Univ. Lille, CHU Lille, LIRIC UMR 995, F-59000, Lille, France.
| |
Collapse
|
29
|
Rementzi K, Böni LJ, Adamcik J, Fischer P, Vlassopoulos D. Structure and dynamics of hagfish mucin in different saline environments. SOFT MATTER 2019; 15:8627-8637. [PMID: 31631202 DOI: 10.1039/c9sm00971j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The defense mechanism of hagfish against predators is based on its ability to form slime within a few milliseconds. Hagfish slime consists of two main components, namely mucin-like glycoproteins and long protein threads, which together entrap vast amounts of water and thus form a highly dilute hydrogel. Here, we investigate the mucin part of this hydrogel, in particular the role of the saline marine environment on the viscoelasticity and structure. By means of dynamic light scattering (DLS), shear and extensional rheology we probe the diffusion dynamics, the flow behavior, and the longest filament breaking time of hagfish mucin solutions. Using DLS we find a concentration-independent diffusion coefficient - characteristic for polyelectrolytes - up to the entanglement regime of 0.2 mg ml-1, which is about ten times higher than the natural concentration of hagfish mucin in hagfish slime. We also observe a slow relaxation process associated with clustering, probably due to electrostatic interactions. Shear rheology further revealed that hagfish mucin possesses pronounced viscoelastic properties at high concentrations (3 mg ml-1), showing that mucin alone achieves mechanical properties similar to those of natural hagfish slime (mucins and protein threads). The main effects of added seawater salts, and predominantly CaCl2 is to reduce the intensity of the slow relaxation process, which suggests that calcium ions lead to an ionotropic gelation of hagfish mucins.
Collapse
Affiliation(s)
- Katerina Rementzi
- FORTH, Institute of Electronic Structure & Laser, N. Plastira 100, 70013 Heraklion, Greece.
| | | | | | | | | |
Collapse
|
30
|
Pinzón Martín S, Seeberger PH, Varón Silva D. Mucins and Pathogenic Mucin-Like Molecules Are Immunomodulators During Infection and Targets for Diagnostics and Vaccines. Front Chem 2019; 7:710. [PMID: 31696111 PMCID: PMC6817596 DOI: 10.3389/fchem.2019.00710] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 10/09/2019] [Indexed: 12/24/2022] Open
Abstract
Mucins and mucin-like molecules are highly O-glycosylated proteins present on the cell surface of mammals and other organisms. These glycoproteins are highly diverse in the apoprotein and glycan cores and play a central role in many biological processes and diseases. Mucins are the most abundant macromolecules in mucus and are responsible for its biochemical and biophysical properties. Mucin-like molecules cover various protozoan parasites, fungi and viruses. In humans, modifications in mucin glycosylation are associated with tumors in epithelial tissue. These modifications allow the distinction between normal and abnormal cell conditions and represent important targets for vaccine development against some cancers. Mucins and mucin-like molecules derived from pathogens are potential diagnostic markers and targets for therapeutic agents. In this review, we summarize the distribution, structure, role as immunomodulators, and the correlation of human mucins with diseases and perform a comparative analysis of mucins with mucin-like molecules present in human pathogens. Furthermore, we review the methods to produce pathogenic and human mucins using chemical synthesis and expression systems. Finally, we present applications of mucin-like molecules in diagnosis and prevention of relevant human diseases.
Collapse
Affiliation(s)
- Sandra Pinzón Martín
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Peter H Seeberger
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Daniel Varón Silva
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| |
Collapse
|
31
|
Ridley C, Lockhart-Cairns MP, Collins RF, Jowitt TA, Subramani DB, Kesimer M, Baldock C, Thornton DJ. The C-terminal dimerization domain of the respiratory mucin MUC5B functions in mucin stability and intracellular packaging before secretion. J Biol Chem 2019; 294:17105-17116. [PMID: 31570524 PMCID: PMC6851316 DOI: 10.1074/jbc.ra119.010771] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/20/2019] [Indexed: 12/19/2022] Open
Abstract
Mucin 5B (MUC5B) has an essential role in mucociliary clearance that protects the pulmonary airways. Accordingly, knowledge of MUC5B structure and its interactions with itself and other proteins is critical to better understand airway mucus biology and improve the management of lung diseases such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). The role of an N-terminal multimerization domain in the supramolecular organization of MUC5B has been previously described, but less is known about its C-terminal dimerization domain. Here, using cryogenic electron microscopy (cryo-EM) and small-angle X-ray scattering (SAXS) analyses of recombinant disulfide-linked dimeric MUC5B dimerization domain we identified an asymmetric, elongated twisted structure, with a double globular base. We found that the dimerization domain is more resistant to disruption than the multimerization domain suggesting the twisted structure of the dimerization domain confers additional stability to MUC5B polymers. Size-exclusion chromatography-multiangle light scattering (SEC-MALS), SPR-based biophysical analyses and microscale thermophoresis of the dimerization domain disclosed no further assembly, but did reveal reversible, calcium-dependent interactions between the dimerization and multimerization domains that were most active at acidic pH, suggesting that these domains have a role in MUC5B intragranular organization. In summary, our results suggest a role for the C-terminal dimerization domain of MUC5B in compaction of mucin chains during granular packaging via interactions with the N-terminal multimerization domain. Our findings further suggest that the less stable multimerization domain provides a potential target for mucin depolymerization to remove mucus plugs in COPD and other lung pathologies.
Collapse
Affiliation(s)
- Caroline Ridley
- Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,Division of Infection Immunity and Respiratory Medicine, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Michael P Lockhart-Cairns
- Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,Division of Cell-Matrix Biology and Regenerative Medicine, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Richard F Collins
- School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Thomas A Jowitt
- Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Durai B Subramani
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7362
| | - Mehmet Kesimer
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7362
| | - Clair Baldock
- Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom .,School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,Division of Cell-Matrix Biology and Regenerative Medicine, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - David J Thornton
- Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom .,Division of Infection Immunity and Respiratory Medicine, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.,Lydia Becker Institute for Immunology and Inflammation, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| |
Collapse
|
32
|
Javitt G, Calvo MLG, Albert L, Reznik N, Ilani T, Diskin R, Fass D. Intestinal Gel-Forming Mucins Polymerize by Disulfide-Mediated Dimerization of D3 Domains. J Mol Biol 2019; 431:3740-3752. [PMID: 31310764 PMCID: PMC6739602 DOI: 10.1016/j.jmb.2019.07.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/03/2019] [Accepted: 07/09/2019] [Indexed: 01/06/2023]
Abstract
The mucin 2 glycoprotein assembles into a complex hydrogel that protects intestinal epithelia and houses the gut microbiome. A major step in mucin 2 assembly is further multimerization of preformed mucin dimers, thought to produce a honeycomb-like arrangement upon hydrogel expansion. Important open questions are how multiple mucin 2 dimers become covalently linked to one another and how mucin 2 multimerization compares with analogous processes in related polymers such as respiratory tract mucins and the hemostasis protein von Willebrand factor. Here we report the x-ray crystal structure of the mucin 2 multimerization module, found to form a dimer linked by two intersubunit disulfide bonds. The dimer structure calls into question the current model for intestinal mucin assembly, which proposes disulfide-mediated trimerization of the same module. Key residues making interactions across the dimer interface are highly conserved in intestinal mucin orthologs, supporting the physiological relevance of the observed quaternary structure. With knowledge of the interface residues, it can be demonstrated that many of these amino acids are also present in other mucins and in von Willebrand factor, further indicating that the stable dimer arrangement reported herein is likely to be shared across this functionally broad protein family. The mucin 2 module structure thus reveals the manner by which both mucins and von Willebrand factor polymerize, drawing deep structural parallels between macromolecular assemblies critical to mucosal epithelia and the vasculature.
Collapse
Affiliation(s)
- Gabriel Javitt
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | | | - Lis Albert
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nava Reznik
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tal Ilani
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ron Diskin
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
| |
Collapse
|
33
|
Abstract
This review describes the organization and importance of mucus in the intestine and lungs in relation to the diseases cystic fibrosis (CF), ulcerative colitis and chronic obstructive pulmonary disease (COPD). The inner surfaces of the body are protected by mucus built around polymeric glycoproteins called mucins. In the disease CF, the small intestinal mucus is in contrast the normal attached to the epithelium, explaining the intestinal problems at this disease. The inner of the two mucus layers of colon is normally impenetrable to bacteria, keeping the commensals away from and protecting the epithelium. This impenetrable property is dependent on the bacterial composition and the host diet, observations that can explain the increased incidence of inflammatory bowel diseases in the western world as bacteria reach the epithelial cells in active ulcerative colitis. The respiratory tract is normally cleared by thick mucus bundles that moved by the cilia sweep the epithelial surface. In CF, the bundles are nonmoving already at birth. Cholinergic stimulations stop the bundle movement explaining some of the beneficial effect of anticholinergic treatment in COPD. In this disease as well as in more developed CF, an attached mucus layer is formed. This mucus has features similar to the protective inner colon mucus and is by this able to separate bacteria from the epithelial surface. When formed in healthy individuals this mucus can be coughed up, but in chronically diseased lungs, bacteria colonizing the mucus will remain in the lungs and the resulting inflammation contribute to the destruction of the lungs.
Collapse
Affiliation(s)
- G C Hansson
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
34
|
Fernandez-Petty CM, Hughes GW, Bowers HL, Watson JD, Rosen BH, Townsend SM, Santos C, Ridley CE, Chu KK, Birket SE, Li Y, Leung HM, Mazur M, Garcia BA, Evans TIA, Libby EF, Hathorne H, Hanes J, Tearney GJ, Clancy JP, Engelhardt JF, Swords WE, Thornton DJ, Wiesmann WP, Baker SM, Rowe SM. A glycopolymer improves vascoelasticity and mucociliary transport of abnormal cystic fibrosis mucus. JCI Insight 2019; 4:125954. [PMID: 30996141 DOI: 10.1172/jci.insight.125954] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/28/2019] [Indexed: 01/05/2023] Open
Abstract
Cystic fibrosis (CF) is characterized by increased mucus viscosity and delayed mucociliary clearance that contributes to progressive decline of lung function. Mucus in the respiratory and GI tract is excessively adhesive in the presence of airway dehydration and excess extracellular Ca2+ upon mucin release, promoting hyperviscous, densely packed mucins characteristic of CF. Therapies that target mucins directly through ionic interactions remain unexploited. Here we show that poly (acetyl, arginyl) glucosamine (PAAG), a polycationic biopolymer suitable for human use, interacts directly with mucins in a Ca2+-sensitive manner to reduce CF mucus viscoelasticity and improve its transport. Notably, PAAG induced a linear structure of purified MUC5B and altered its sedimentation profile and viscosity, indicative of proper mucin expansion. In vivo, PAAG nebulization improved mucociliary transport in CF rats with delayed mucus clearance, and cleared mucus plugging in CF ferrets. This study demonstrates the potential use of a synthetic glycopolymer PAAG as a molecular agent that could benefit patients with a broad array of mucus diseases.
Collapse
Affiliation(s)
| | - Gareth W Hughes
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, United Kingdom
| | - Hannah L Bowers
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA
| | - John D Watson
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA
| | - Bradley H Rosen
- Department of Anatomy & Cell Biology and.,Department of Medicine, University of Iowa, Iowa City, Iowa, USA
| | | | | | - Caroline E Ridley
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, United Kingdom
| | - Kengyeh K Chu
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Dermatology, Massachusetts General Hospital, Boston, Massachusetts, USA,Harvard Medical School, Boston, Massachusetts, USA.,Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA.,Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Susan E. Birket
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center
| | - Yao Li
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center
| | - Hui Min Leung
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Dermatology, Massachusetts General Hospital, Boston, Massachusetts, USA,Harvard Medical School, Boston, Massachusetts, USA.,Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA.,Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Marina Mazur
- Gregory Fleming James Cystic Fibrosis Research Center
| | - Bryan A Garcia
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center
| | | | | | - Heather Hathorne
- Gregory Fleming James Cystic Fibrosis Research Center,Department of Pediatrics, UAB, Birmingham, Alabama, USA
| | - Justin Hanes
- Center for Nanomedicine and Departments of Biomedical Engineering, Chemical & Biomolecular Sciences, Johns Hopkins University, Baltimore, Maryland, USA
| | - Guillermo J Tearney
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA.,Department of Dermatology, Massachusetts General Hospital, Boston, Massachusetts, USA,Harvard Medical School, Boston, Massachusetts, USA.,Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA.,Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - John P Clancy
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - John F Engelhardt
- Department of Anatomy & Cell Biology and.,Department of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - William E Swords
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center
| | - David J Thornton
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, United Kingdom
| | | | | | - Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham (UAB), Birmingham, Alabama, USA.,Gregory Fleming James Cystic Fibrosis Research Center,Department of Pediatrics, UAB, Birmingham, Alabama, USA.,Department of Cell Developmental & Integrative Biology, UAB, Birmingham, Alabama, USA
| |
Collapse
|
35
|
Erickson-DiRenzo E, Leydon C, Thibeault SL. Methodology for the establishment of primary porcine vocal fold epithelial cell cultures. Laryngoscope 2019; 129:E355-E364. [PMID: 30848488 DOI: 10.1002/lary.27909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 02/04/2019] [Accepted: 02/12/2019] [Indexed: 01/10/2023]
Abstract
OBJECTIVE A current lack of methods for epithelial cell culture significantly hinders our understanding of the role of the epithelial and mucus barriers in vocal fold health and disease. Our first objective was to establish reproducible techniques for the isolation and culture of primary porcine vocal fold epithelial cells. Our second objective was to evaluate the functional significance of cell cultures using an in vitro exposure to an inflammatory cytokine. METHODS Epithelial cells were isolated from porcine vocal folds and expanded in culture. Characterization of cultures was completed by immunostaining with markers for pan-cytokeratin (epithelial cells), vimentin (stromal cells), von Willebrand factor (endothelial cell), and MUC1 and MUC4 (mucin) glycoproteins. Established epithelial cell cultures were then exposed to the inflammatory cytokine tumor necrosis factor alpha (TNF-α) for 24-hours, and transcript expression of MUC1 and MUC4 was evaluated. RESULTS Reproducible, porcine vocal fold epithelial cell cultures, demonstrating cobblestone appearance characteristic of the typical morphology of epithelial cell cultures were created. Cells showed positive staining for pan-cytokeratin with limited expression of vimentin and von Willebrand factor. Epithelial cells also expressed MUC1 and MUC4. TNF-α significantly increased transcript expression of MUC4. CONCLUSION Here, we present the first report of successful culture of primary porcine vocal fold epithelial cells. Cultures will provide researchers with a valuable new in vitro tool to investigate vocal fold epithelium and mucus as well as the effects of common challenges, including inflammatory cytokines, on these barriers. LEVEL OF EVIDENCE NA Laryngoscope, 129:E355-E364, 2019.
Collapse
Affiliation(s)
- Elizabeth Erickson-DiRenzo
- Department of Surgery, Division of Otolaryngology-Head & Neck Surgery, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Ciara Leydon
- Department of Surgery, Division of Otolaryngology-Head & Neck Surgery, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Susan L Thibeault
- Department of Surgery, Division of Otolaryngology-Head & Neck Surgery, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| |
Collapse
|
36
|
Demouveaux B, Gouyer V, Magnien M, Plet S, Gottrand F, Narita T, Desseyn JL. [Gel-forming mucins structure governs mucus gels viscoelasticity]. Med Sci (Paris) 2018; 34:806-812. [PMID: 30451674 DOI: 10.1051/medsci/2018206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mucus is the first line of innate mucosal defense in all mammals. Gel‑forming mucins control the rheological properties of mucus hydrogels by forming a network in which hydrophilic and hydrophobic regions coexist, and it has been revealed that the network is formed through both covalent links and reversible links such as hydrophobic interactions in order to modulate the structure as a function of the physiological necessities. Here, we review the structure and functions of the mucus in terms of the gel-forming mucins protein-protein interactions, also called interactome. Since it is difficult to characterize the low energy reversible interactions due to their dependence on physico-chemical environment, their role is not well understood. Still, they constitute a promising target to counteract mucus abnormalities observed in mucus-associated diseases.
Collapse
Affiliation(s)
- Bastien Demouveaux
- Inserm, Université de Lille, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Valérie Gouyer
- Inserm, Université de Lille, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Mylène Magnien
- Inserm, Université de Lille, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Ségolène Plet
- Inserm, Université de Lille, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Frédéric Gottrand
- Inserm, Université de Lille, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Tetsuharu Narita
- PSL Research University, UPMC Univ. Paris 06, ESPCI Paris, CNRS UMR 7615, Laboratoire Sciences et Ingénierie de la Matière Molle, 10, rue Vauquelin, 75231, Paris Cedex 05, France - Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japon
| | - Jean-Luc Desseyn
- Inserm, Université de Lille, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| |
Collapse
|
37
|
Yamashita MSDA, Melo EO. Mucin 2 (MUC2) promoter characterization: an overview. Cell Tissue Res 2018; 374:455-463. [PMID: 30218241 DOI: 10.1007/s00441-018-2916-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 08/13/2018] [Indexed: 12/24/2022]
Abstract
Transgenic livestock have been studied with a well-known interest in improving quantitative and qualitative traits. In order to direct heterologous gene expression, it is indispensable to identify and characterize a promoter suitable for directing the expression of the gene of interest (GOI) in a tissue-specific way. The gastrointestinal tract is a desirable target for gene expression in several mammalian models. Throughout the surface of the intestinal epithelium, there is an intricate polymer network, formed by gel-forming mucins (especially MUC2 and MUC5AC, of which MUC2 is the major one), which plays a protective role due to the formation of a physical, chemical and immunological barrier between the organism and the environment. The characterization of the gel-forming mucins is difficult because of their large size and repetitive DNA sequences and domains. The main mucin in the small and large intestine, mucin 2 (MUC2), is expressed specifically in goblet cells. MUC2 plays an important role in intestinal homeostasis and its disruption is associated with several diseases and carcinomas. This mucin is also an important marker for elucidating mechanisms that regulate differentiation of the secretory cell lineage. This review presents the state of the art of MUC2 promoter structure and functional characterization.
Collapse
Affiliation(s)
| | - Eduardo O Melo
- EMBRAPA Genetic Resources and Biotechnology, PqEB Av W5 Norte, Brasilia, DF, 70770-917, Brazil
| |
Collapse
|
38
|
Fernández-Blanco JA, Fakih D, Arike L, Rodríguez-Piñeiro AM, Martínez-Abad B, Skansebo E, Jackson S, Root J, Singh D, McCrae C, Evans CM, Åstrand A, Ermund A, Hansson GC. Attached stratified mucus separates bacteria from the epithelial cells in COPD lungs. JCI Insight 2018; 3:120994. [PMID: 30185674 DOI: 10.1172/jci.insight.120994] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/31/2018] [Indexed: 02/02/2023] Open
Abstract
The respiratory tract is normally kept essentially free of bacteria by cilia-mediated mucus transport, but in chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF), bacteria and mucus accumulates instead. To address the mechanisms behind the mucus accumulation, the proteome of bronchoalveolar lavages from COPD patients and mucus collected in an elastase-induced mouse model of COPD was analyzed, revealing similarities with each other and with the protein content in colonic mucus. Moreover, stratified laminated sheets of mucus were observed in airways from patients with CF and COPD and in elastase-exposed mice. On the other hand, the mucus accumulation in the elastase model was reduced in Muc5b-KO mice. While mucus plugs were removed from airways by washing with hypertonic saline in the elastase model, mucus remained adherent to epithelial cells. Bacteria were trapped on this mucus, whereas, in non-elastase-treated mice, bacteria were found on the epithelial cells. We propose that the adherence of mucus to epithelial cells observed in CF, COPD, and the elastase-induced mouse model of COPD separates bacteria from the surface cells and, thus, protects the respiratory epithelium.
Collapse
Affiliation(s)
- Joan Antoni Fernández-Blanco
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden.,Bioscience, Respiratory, Inflammation and Autoimmunity, IMED Biotech Unit, AstraZeneca Gothenburg, Gothenburg, Sweden
| | - Dalia Fakih
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Liisa Arike
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | | | | | - Elin Skansebo
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Sonya Jackson
- Bioscience, Respiratory, Inflammation and Autoimmunity, IMED Biotech Unit, AstraZeneca Gothenburg, Gothenburg, Sweden
| | - James Root
- Bioscience, Respiratory, Inflammation and Autoimmunity, IMED Biotech Unit, AstraZeneca Gothenburg, Gothenburg, Sweden
| | - Dave Singh
- Medicines Evaluation Unit, University of Manchester, Manchester, United Kingdom
| | - Christopher McCrae
- Bioscience, Respiratory, Inflammation and Autoimmunity, IMED Biotech Unit, AstraZeneca Gothenburg, Gothenburg, Sweden
| | | | - Annika Åstrand
- Bioscience, Respiratory, Inflammation and Autoimmunity, IMED Biotech Unit, AstraZeneca Gothenburg, Gothenburg, Sweden
| | - Anna Ermund
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Gunnar C Hansson
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
39
|
Ermund A, Meiss LN, Dolan B, Bähr A, Klymiuk N, Hansson GC. The mucus bundles responsible for airway cleaning are retained in cystic fibrosis and by cholinergic stimulation. Eur Respir J 2018; 52:13993003.00457-2018. [PMID: 29853489 DOI: 10.1183/13993003.00457-2018] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/17/2018] [Indexed: 02/04/2023]
Abstract
The beneficial effect of anticholinergic therapy for chronic lung diseases such as chronic obstructive pulmonary disease (COPD) is well documented, although cholinergic stimulation paradoxically inhibits liquid absorption, increases ciliary beat frequency and increases airway surface liquid transport.Using pig tracheobronchial explants, we quantified basal mucus transport before as well as after incubation with the clinically used antimuscarinic compound ipratropium bromide (Atrovent) and stimulation with acetylcholine.As expected, surface liquid transport was increased by acetylcholine and carbachol. In contrast, the mucus bundles secreted from the submucosal glands normally transported on the cilia were stopped from moving by acetylcholine, an effect inhibited by ipratropium bromide. Interestingly, in pigs lacking a functional cystic fibrosis (CF) transmembrane conductance regulator (CFTR) channel, the mucus bundles were almost immobile. As in wild-type pigs, CF surface liquid transport increased after carbachol stimulation. The stagnant CF mucus bundles were trapped on the tracheal surface attached to the surface goblet cells. Pseudomonas aeruginosa bacteria were moved by the mucus bundles in wild-type but not CF pigs.Acetylcholine thus uncouples airway surface liquid transport from transport of the surface mucus bundles as the bundles are dynamically inhibited by acetylcholine and the CFTR channel, explaining initiation of CF and COPD, and opening novel therapeutic windows.
Collapse
Affiliation(s)
- Anna Ermund
- Dept of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Lauren N Meiss
- Dept of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Brendan Dolan
- Dept of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Andrea Bähr
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Nikolai Klymiuk
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Gunnar C Hansson
- Dept of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
40
|
Mucins: the frontline defence of the lung. Biochem Soc Trans 2018; 46:1099-1106. [PMID: 30154090 PMCID: PMC6195635 DOI: 10.1042/bst20170402] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 02/07/2023]
Abstract
Mucus plays a vital role in protecting the lungs from environmental factors, but conversely, in muco-obstructive airway disease, mucus becomes pathologic. In its protective role, mucus entraps microbes and particles removing them from the lungs via the co-ordinated beating of motile cilia. This mechanism of lung defence is reliant upon a flowing mucus gel, and the major macromolecular components that determine the rheological properties of mucus are the polymeric mucins, MUC5AC and MUC5B. These large O-linked glycoproteins have direct roles in maintaining lung homeostasis. MUC5B is essential for interaction with the ciliary clearance system and MUC5AC is up-regulated in response to allergic inflammatory challenge. Mucus with abnormal biophysical properties is a feature of muco-obstructive respiratory disease and can result from many different mechanisms including alterations in mucin polymer assembly, mucin concentration and the macromolecular form in mucus, as well as changes in airway surface hydration, pH and ion composition. The abnormal mucus results in defective lung protection via compromised ciliary clearance, leading to infection and inflammation.
Collapse
|
41
|
Böni LJ, Zurflüh R, Baumgartner ME, Windhab EJ, Fischer P, Kuster S, Rühs PA. Effect of ionic strength and seawater cations on hagfish slime formation. Sci Rep 2018; 8:9867. [PMID: 29959378 PMCID: PMC6026207 DOI: 10.1038/s41598-018-27975-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 06/13/2018] [Indexed: 11/09/2022] Open
Abstract
The defensive slime of hagfish consists of a polyanionic mucin hydrogel that synergistically interacts with a fiber network forming a coherent and elastic hydrogel in high ionic strength seawater. In seawater, the slime deploys in less than a second entrapping large quantities of water by a well-timed thread skein unravelling and mucous gel swelling. This rapid and vast hydrogel formation is intriguing, as high ionic strength conditions generally counteract the swelling speed and ratio of polyelectrolyte hydrogels. In this work we investigate the effect of ionic strength and seawater cations on slime formation dynamics and functionality. In the absence of ionic strength skeins swell radially and unravel uncontrolled, probably causing tangling and creating a confined thread network that entraps limited water. At high ionic strength skeins unravel, but create a collapsed and dense fiber network. High ionic strength conditions therefore seem crucial for controlled skein unraveling, however not sufficient for water retention. Only the presence of naturally occurring Ca2+ or Mg2+-ions allowed for an expanded network and full water retention probably due to Ca2+-mediated vesicle rupture and cross-linking of the mucin. Our study demonstrates that hagfish slime deployment is a well-timed, ionic-strength, and divalent-cation dependent dynamic hydrogel formation process.
Collapse
Affiliation(s)
- L J Böni
- Department of Health Science and Technology, ETH Zürich, 8092, Zürich, Switzerland.
| | - R Zurflüh
- Department of Health Science and Technology, ETH Zürich, 8092, Zürich, Switzerland
| | - M E Baumgartner
- Department of Health Science and Technology, ETH Zürich, 8092, Zürich, Switzerland
| | - E J Windhab
- Department of Health Science and Technology, ETH Zürich, 8092, Zürich, Switzerland
| | - P Fischer
- Department of Health Science and Technology, ETH Zürich, 8092, Zürich, Switzerland
| | - S Kuster
- Department of Health Science and Technology, ETH Zürich, 8092, Zürich, Switzerland
| | - P A Rühs
- Department of Materials, ETH Zürich, 8093, Zürich, Switzerland
- Department of Bioengineering and Materials Science and Engineering, University of California, Berkeley, California, 94720-1760, USA
| |
Collapse
|
42
|
Role of mucins in lung homeostasis: regulated expression and biosynthesis in health and disease. Biochem Soc Trans 2018; 46:707-719. [PMID: 29802217 DOI: 10.1042/bst20170455] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 04/24/2018] [Accepted: 04/26/2018] [Indexed: 01/02/2023]
Abstract
In humans and mice, the first line of innate defense against inhaled pathogens and particles in the respiratory tract is airway mucus. The primary solid components of the mucus layer are the mucins MUC5AC and MUC5B, polymeric glycoproteins whose changes in abundance and structure can dramatically affect airway defense. Accordingly, MUC5AC/Muc5ac and MUC5B/Muc5b are tightly regulated at a transcriptional level by tissue-specific transcription factors in homeostasis and in response to injurious and inflammatory triggers. In addition to modulated levels of mucin gene transcription, translational and post-translational biosynthetic processes also exert significant influence upon mucin function. Mucins are massive macromolecules with numerous functional domains that contribute to their structural composition and biophysical properties. Single MUC5AC and MUC5B apoproteins have molecular masses of >400 kDa, and von Willebrand factor D-like as well as other cysteine-rich domain segments contribute to mucin polymerization and flexibility, thus increasing apoprotein length and complexity. Additional domains serve as sites for O-glycosylation, which increase further mucin mass several-fold. Glycosylation is a defining process for mucins that is specific with respect to additions of glycans to mucin apoprotein backbones, and glycan additions influence the physical properties of the mucins via structural modifications as well as charge interactions. Ultimately, through their tight regulation and complex assembly, airway mucins follow the biological rule of 'form fits function' in that their structural organization influences their role in lung homeostatic mechanisms.
Collapse
|
43
|
Trillo-Muyo S, Nilsson HE, Recktenwald CV, Ermund A, Ridley C, Meiss LN, Bähr A, Klymiuk N, Wine JJ, Koeck PJB, Thornton DJ, Hebert H, Hansson GC. Granule-stored MUC5B mucins are packed by the non-covalent formation of N-terminal head-to-head tetramers. J Biol Chem 2018; 293:5746-5754. [PMID: 29440393 PMCID: PMC5900763 DOI: 10.1074/jbc.ra117.001014] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/08/2018] [Indexed: 12/20/2022] Open
Abstract
Most MUC5B mucin polymers in the upper airways of humans and pigs are produced by submucosal glands. MUC5B forms N-terminal covalent dimers that are further packed into larger assemblies because of low pH and high Ca2+ in the secretory granule of the mucin-producing cell. We purified the recombinant MUC5B N-terminal covalent dimer and used single-particle electron microscopy to study its structure under intracellular conditions. We found that, at intragranular pH, the dimeric MUC5B organized into head-to-head noncovalent tetramers where the von Willebrand D1-D2 domains hooked into each other. These N-terminal tetramers further formed long linear complexes from which, we suggest, the mucin domains and their C termini project radially outwards. Using conventional and video microscopy, we observed that, upon secretion into the submucosal gland ducts, a flow of bicarbonate-rich fluid passes the mucin-secreting cells. We suggest that this unfolds and pulls out the MUC5B assemblies into long linear threads. These further assemble into thicker mucin bundles in the glandular ducts before emerging at the gland duct opening. We conclude that the combination of intracellular packing of the MUC5B mucin and the submucosal gland morphology creates an efficient machine for producing linear mucin bundles.
Collapse
Affiliation(s)
- Sergio Trillo-Muyo
- From the Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Harriet E Nilsson
- From the Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden
- the Department of Biosciences and Nutrition, Karolinska Institutet, 14157 Huddinge, Sweden
- the School of Technology and Health, KTH Royal Institute of Technology, 14157 Huddinge, Sweden
| | - Christian V Recktenwald
- From the Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Anna Ermund
- From the Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Caroline Ridley
- the Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M139PT, United Kingdom
| | - Lauren N Meiss
- From the Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Andrea Bähr
- the Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig Maximilians University Munich, Hackerstrasse 27, 85764 Oberschleissheim, Germany, and
| | - Nikolai Klymiuk
- the Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig Maximilians University Munich, Hackerstrasse 27, 85764 Oberschleissheim, Germany, and
| | - Jeffrey J Wine
- the Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California 94305
| | - Philip J B Koeck
- the Department of Biosciences and Nutrition, Karolinska Institutet, 14157 Huddinge, Sweden
- the School of Technology and Health, KTH Royal Institute of Technology, 14157 Huddinge, Sweden
| | - David J Thornton
- the Wellcome Trust Centre for Cell-Matrix Research, Faculty of Biology, Medicine, and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M139PT, United Kingdom
| | - Hans Hebert
- the Department of Biosciences and Nutrition, Karolinska Institutet, 14157 Huddinge, Sweden
- the School of Technology and Health, KTH Royal Institute of Technology, 14157 Huddinge, Sweden
| | - Gunnar C Hansson
- From the Department of Medical Biochemistry, University of Gothenburg, 40530 Gothenburg, Sweden,
| |
Collapse
|
44
|
Meldrum OW, Yakubov GE, Bonilla MR, Deshmukh O, McGuckin MA, Gidley MJ. Mucin gel assembly is controlled by a collective action of non-mucin proteins, disulfide bridges, Ca 2+-mediated links, and hydrogen bonding. Sci Rep 2018; 8:5802. [PMID: 29643478 PMCID: PMC5895598 DOI: 10.1038/s41598-018-24223-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 03/27/2018] [Indexed: 12/24/2022] Open
Abstract
Mucus is characterized by multiple levels of assembly at different length scales which result in a unique set of rheological (flow) and mechanical properties. These physical properties determine its biological function as a highly selective barrier for transport of water and nutrients, while blocking penetration of pathogens and foreign particles. Altered integrity of the mucus layer in the small intestine has been associated with a number of gastrointestinal tract pathologies such as Crohn’s disease and cystic fibrosis. In this work, we uncover an intricate hierarchy of intestinal mucin (Muc2) assembly and show how complex rheological properties emerge from synergistic interactions between mucin glycoproteins, non-mucin proteins, and Ca2+. Using a novel method of mucus purification, we demonstrate the mechanism of assembly of Muc2 oligomers into viscoelastic microscale domains formed via hydrogen bonding and Ca2+-mediated links, which require the joint presence of Ca2+ ions and non-mucin proteins. These microscale domains aggregate to form a heterogeneous yield stress gel-like fluid, the macroscopic rheological properties of which are virtually identical to that of native intestinal mucus. Through proteomic analysis, we short-list potential protein candidates implicated in mucin assembly, thus paving the way for identifying the molecules responsible for the physiologically critical biophysical properties of mucus.
Collapse
Affiliation(s)
- Oliver W Meldrum
- ARC Centre of Excellence in Plant Cell Walls, The University of Queensland, St Lucia, 4072, Qld, Australia.,Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, 4072, Qld, Australia
| | - Gleb E Yakubov
- ARC Centre of Excellence in Plant Cell Walls, The University of Queensland, St Lucia, 4072, Qld, Australia. .,School of Chemical Engineering, The University of Queensland, St Lucia, 4072, Qld, Australia.
| | - Mauricio R Bonilla
- ARC Centre of Excellence in Plant Cell Walls, The University of Queensland, St Lucia, 4072, Qld, Australia.,School of Chemical Engineering, The University of Queensland, St Lucia, 4072, Qld, Australia
| | - Omkar Deshmukh
- School of Chemical Engineering, The University of Queensland, St Lucia, 4072, Qld, Australia
| | - Michael A McGuckin
- Chronic Disease Biology and Care Program, Mater Research Institute - The University of Queensland, Translational Research Institute, Woolloongabba, QLD 4102, Australia
| | - Michael J Gidley
- ARC Centre of Excellence in Plant Cell Walls, The University of Queensland, St Lucia, 4072, Qld, Australia.,Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, 4072, Qld, Australia
| |
Collapse
|
45
|
Demouveaux B, Gouyer V, Gottrand F, Narita T, Desseyn JL. Gel-forming mucin interactome drives mucus viscoelasticity. Adv Colloid Interface Sci 2018; 252:69-82. [PMID: 29329667 DOI: 10.1016/j.cis.2017.12.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 12/31/2022]
Abstract
Mucus is a hydrogel that constitutes the first innate defense in all mammals. The main organic component of mucus, gel-forming mucins, forms a complex network through both reversible and irreversible interactions that drive mucus gel formation. Significant advances in the understanding of irreversible gel-forming mucins assembly have been made using recombinant protein approaches. However, little is known about the reversible interactions that may finely modulate mucus viscoelasticity, which can be characterized using rheology. This approach can be used to investigate both the nature of gel-forming mucins interactions and factors that influence hydrogel formation. This knowledge is directly relevant to the development of new drugs to modulate mucus viscoelasticity and to restore normal mucus functions in diseases such as in cystic fibrosis. The aim of the present review is to summarize the current knowledge about the relationship between the mucus protein matrix and its functions, with emphasis on mucus viscoelasticity.
Collapse
Affiliation(s)
| | - Valérie Gouyer
- Univ. Lille, Inserm, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Frédéric Gottrand
- Univ. Lille, Inserm, CHU Lille, LIRIC UMR 995, F-59000 Lille, France
| | - Tetsuharu Narita
- Laboratoire Sciences et Ingénierie de la Matière Molle, PSL Research University, UPMC Univ Paris 06, ESPCI Paris, CNRS, 10 rue Vauquelin, 75231 Paris Cedex 05, France; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Jean-Luc Desseyn
- Univ. Lille, Inserm, CHU Lille, LIRIC UMR 995, F-59000 Lille, France.
| |
Collapse
|
46
|
A slippery slope: On the origin, role and physiology of mucus. Adv Drug Deliv Rev 2018; 124:16-33. [PMID: 29108861 DOI: 10.1016/j.addr.2017.10.014] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/17/2017] [Accepted: 10/29/2017] [Indexed: 02/07/2023]
Abstract
The mucosa of the gastrointestinal tract, eyes, nose, lungs, cervix and vagina is lined by epithelium interspersed with mucus-secreting goblet cells, all of which contribute to their unique functions. This mucus provides an integral defence to the epithelium against noxious agents and pathogens. However, it can equally act as a barrier to drugs and delivery systems targeting epithelial passive and active transport mechanisms. This review highlights the various mucins expressed at different mucosal surfaces on the human body, and their role in creating a mucoid architecture to protect epithelia with specialized functions. Various factors compromising the barrier properties of mucus have been discussed, with an emphasis on how disease states and microbiota can alter the physical properties of mucus. For instance, Akkermansia muciniphila, a bacterium found in higher levels in the gut of lean individuals induces the production of a thickened gut mucus layer. The aims of this article are to elucidate the different physiological, biochemical and physical properties of bodily mucus, a keen appreciation of which will help circumvent the slippery slope of challenges faced in achieving effective mucosal drug and gene delivery.
Collapse
|
47
|
Functional characterization of the mucus barrier on the Xenopus tropicalis skin surface. Proc Natl Acad Sci U S A 2018; 115:726-731. [PMID: 29311327 PMCID: PMC5789918 DOI: 10.1073/pnas.1713539115] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The production of mucus helps to trap pathogens, preventing their entry into the body, while it also acts as an interface for many important physiological events (e.g., gas and nutrient exchange). In mammalian models, a detailed study of mucus and its component parts is hindered by the difficulty in accessing these internally located tissues. The Xenopus tropicalis tadpole skin offers a complementary nonmammalian model system to study mucosal epithelia. Using this, we identify a mucin, similar to human mucins, that protects against infection. This system offers an experimentally tractable approach to study mucins and the mucus barrier and their role in conferring protection at mucosal surfaces. Mucosal surfaces represent critical routes for entry and exit of pathogens. As such, animals have evolved strategies to combat infection at these sites, in particular the production of mucus to prevent attachment and to promote subsequent movement of the mucus/microbe away from the underlying epithelial surface. Using biochemical, biophysical, and infection studies, we have investigated the host protective properties of the skin mucus barrier of the Xenopus tropicalis tadpole. Specifically, we have characterized the major structural component of the barrier and shown that it is a mucin glycoprotein (Otogelin-like or Otogl) with similar sequence, domain organization, and structural properties to human gel-forming mucins. This mucin forms the structural basis of a surface barrier (∼6 μm thick), which is depleted through knockdown of Otogl. Crucially, Otogl knockdown leads to susceptibility to infection by the opportunistic pathogen Aeromonas hydrophila. To more accurately reflect its structure, tissue localization, and function, we have renamed Otogl as Xenopus Skin Mucin, or MucXS. Our findings characterize an accessible and tractable model system to define mucus barrier function and host–microbe interactions.
Collapse
|
48
|
Ermund A, Recktenwald CV, Skjåk-Braek G, Meiss LN, Onsøyen E, Rye PD, Dessen A, Myrset AH, Hansson GC. OligoG CF-5/20 normalizes cystic fibrosis mucus by chelating calcium. Clin Exp Pharmacol Physiol 2018; 44:639-647. [PMID: 28261854 DOI: 10.1111/1440-1681.12744] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 02/06/2023]
Abstract
The goal of this study was to determine whether the guluronate (G) rich alginate OligoG CF-5/20 (OligoG) could detach cystic fibrosis (CF) mucus by calcium chelation, which is also required for normal mucin unfolding. Since bicarbonate secretion is impaired in CF, leading to insufficient mucin unfolding and thereby attached mucus, and since bicarbonate has the ability to bind calcium, we hypothesized that the calcium chelating property of OligoG would lead to detachment of CF mucus. Indeed, OligoG could compete with the N-terminus of the MUC2 mucin for calcium binding as shown by microscale thermophoresis. Further, effects on mucus thickness and attachment induced by OligoG and other alginate fractions of different length and composition were evaluated in explants of CF mouse ileum mounted in horizontal Ussing-type chambers. OligoG at 1.5% caused effective detachment of CF mucus and the most potent alginate fraction tested, the poly-G fraction of about 12 residues, had similar potency compared to OligoG whereas mannuronate-rich (M) polymers had minimal effect. In conclusion, OligoG binds calcium with appropriate affinity without any overt harmful effect on the tissue and can be exploited for treating mucus stagnation.
Collapse
Affiliation(s)
- Anna Ermund
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | | | - Gudmund Skjåk-Braek
- Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Lauren N Meiss
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| | | | | | | | | | - Gunnar C Hansson
- Department of Medical Biochemistry, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
49
|
Bonser LR, Erle DJ. Airway Mucus and Asthma: The Role of MUC5AC and MUC5B. J Clin Med 2017; 6:jcm6120112. [PMID: 29186064 PMCID: PMC5742801 DOI: 10.3390/jcm6120112] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 11/25/2017] [Accepted: 11/27/2017] [Indexed: 11/16/2022] Open
Abstract
Asthma is characterized by mucus abnormalities. Airway epithelial hyperplasia and metaplasia result in changes in stored and secreted mucin and the production of a pathologic mucus gel. Mucus transport is impaired, culminating in mucus plugging and airway obstruction—a major cause of morbidity in asthma. The polymeric mucins MUC5AC and MUC5B are integral components of airway mucus. MUC5AC and MUC5B gene expression is altered in asthma, and recent work sheds light on their contribution to asthma pathogenesis. Herein, we review our current understanding of the role of MUC5AC and MUC5B in mucus dysfunction in asthma.
Collapse
Affiliation(s)
- Luke R Bonser
- Lung Biology Center, University of California San Francisco, San Francisco, CA 94143, USA.
| | - David J Erle
- Lung Biology Center, University of California San Francisco, San Francisco, CA 94143, USA.
| |
Collapse
|
50
|
The normal trachea is cleaned by MUC5B mucin bundles from the submucosal glands coated with the MUC5AC mucin. Biochem Biophys Res Commun 2017; 492:331-337. [PMID: 28859985 PMCID: PMC5596833 DOI: 10.1016/j.bbrc.2017.08.113] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 08/27/2017] [Indexed: 11/23/2022]
Abstract
To understand the mucociliary clearance system, mucins were visualized by light, confocal and electron microscopy, and mucus was stained by Alcian blue and tracked by video microscopy on tracheal explants of newborn piglets. We observed long linear mucus bundles that appeared at the submucosal gland openings and were transported cephalically. The mucus bundles were shown by mass spectrometry and immunostaining to have a core made of MUC5B mucin and were coated with MUC5AC mucin produced by surface goblet cells. The transport speed of the bundles was slower than the airway surface liquid flow. We suggest that the goblet cell MUC5AC mucin anchors the mucus bundles and thus controls their transport. Normal clearance of the respiratory tree of pigs and humans, both rich in submucosal glands, is performed by thick and long mucus bundles. Submucosal glands in the piglet trachea form bundles of MUC5B mucin. The mucus bundles are coated with MUC5AC mucin produced by surface goblet cells. The mucus bundles are transported 10-times slower than the airway surface liquid. The surface goblet cells are suggested to control the mucus bundle movement.
Collapse
|